preproenkephalin and Lung-Neoplasms

Functional evidence suggests that opioid peptides such as dynorphin are involved in the regulation of airway macrophage functions and of human cancer growth. However, anatomical evidence for components of a putative dynorphin network within lung cancer patients is scarce. Tissue from lung cancer patients was examined immunohistochemically for all components of a local dynorphin (DYN) network. Double immunofluorescence microscopy analysis revealed colocalization of the opioid precursor PDYN with its end-product DYN, and key processing enzymes prohormone convertases 1 and 2 and carboxypeptidase E, as well as the kappa-opioid receptor (KOR) within alveolar macrophages and cancerous cells in varying degrees among patients. Moreover, chromograninA-immunoreactive pulmonary neuroendocrine cells expressing DYN were close to substance P- and KOR-immunoreactive sensory nerves. Our findings give a first hint of a neuroanatomical basis for a peripheral DYN network, conceivably regulating pulmonary, immune and cell-proliferative functions within the human lung, most likely in a paracrine/autocrine fashion.

Topics: Aged; Biomarkers, Tumor; Bronchi; Carboxypeptidase H; Carcinoma; Dynorphins; Enkephalins; Female; Fluorescent Antibody Technique, Indirect; Humans; Immunoenzyme Techniques; Lung Neoplasms; Macrophages, Alveolar; Male; Microscopy, Fluorescence; Middle Aged; Neurotransmitter Agents; Proprotein Convertase 1; Proprotein Convertase 2; Protein Precursors; Receptors, Opioid, kappa; Respiratory Mucosa

Prodynorphin gene transcripts have been characterized in human tissues with cRNA probes covering parts of the non-coding exon 1 and the main coding exon 4 using Northern blot and RNase protection experiments. A 2.8-kb signal was observed in human brain RNA with both the exon 1 and exon 4 probes. An RNase protection assay with the exon 1 probe, performed to map the 5' end of this transcript, produced protected fragments in the range of 0.11 to 0.15 kb indicating that exon 1 is 1.2 kb shorter than previously proposed. 5'-RACE-PCR and sequencing of amplified cDNA fragments confirmed this assignment. In adrenal gland, testis and the human small cell lung carcinoma cell line, U1690, several prodynorphin-like mRNAs structurally different from the brain prodynorphin mRNA species were observed.

Topics: Adrenal Glands; Base Sequence; Brain; Carcinoma, Small Cell; Cell Line; Enkephalins; Exons; Gene Expression; Humans; Lung Neoplasms; Male; Molecular Sequence Data; Organ Specificity; Polymerase Chain Reaction; Protein Biosynthesis; Protein Precursors; RNA Probes; RNA, Messenger; Testis; Transcription, Genetic; Tumor Cells, Cultured

The prodynorphin gene contains several kappa B motifs, suggesting that kappa B-specific DNA-binding factors may regulate its expression. Prodynorphin is known to be expressed in human tumor cell lines [Geiger et al., Regul. Peptides, 34 (1991) 181-188] and we report here that several DNA-binding factors of the NF-kappa B/c-Rel-family are present in the same cells. Three main kappa B-specific factors, presumably a p50 homodimer, NF-kappa B which is a p50/p65 heterodimer and a p65/c-Rel heterodimer were identified using an electromobility shift assay (EMSA), immunoabsorption and UV cross-linking experiments. Minor factors consisting of a novel kappa B-specific protein of about 125 kDa (p125) or being hetero-oligomeric, composed of p125 and either of three other subunits, namely p50, p65 and c-Rel, were also identified. The homo-oligomer of p125 may be identical to the kappa B-specific factor BETA, previously found only in brain [Korner et al., Neuron, 3 (1989) 563-572]. Comparison of prodynorphin mRNA levels with levels of the kappa B-specific DNA-binding factors revealed a negative correlation with the level of p50 homodimer, and a positive correlation with the ratio of the levels of p65/c-Rel to NF-kappa B. No association was found with proenkephalin mRNA levels which were significant in only one cell line. The p50 homodimer, but not p65/c-Rel and NF-kappa B, bound specifically to a DNA-motif within the dynorphin A-encoding gene sequence. This sequence is located in exon 4 and similar to the consensus kappa B-sequence. The dynorphin A-encoding sequence may represent an intragenic target for the p50 homodimer, which when bound to the sequence suppresses transcription.

Topics: Animals; Base Sequence; Binding Sites; Cell Line; Choriocarcinoma; Enkephalins; Gene Expression; Humans; Lung Neoplasms; Molecular Sequence Data; Neuroblastoma; NF-kappa B; Oligodeoxyribonucleotides; Oligonucleotide Probes; Protein Precursors; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-rel; Rats; Sequence Homology, Nucleic Acid; Swine; Tumor Cells, Cultured